ANTIFERROMAGNETIC ORDER IN SUPERCONDUCTING UPT3 - AN X-RAY MAGNETIC SCATTERING STUDY

The temperature dependence of the antiferromagnetic order in supercond ucting UPt3 has been measured using x-ray resonance magnetic scatterin g. The magnetic Bragg intensity at Q=(1/2,0,2) grows linearly from T-N =5 K to T congruent to 0.6 K (T-C+=0.53 K), where it becomes suppresse d with temperature to a reduction of similar to 6% at T=180 mK. These results demonstrate a coupling of the superconducting and antiferromag netic order parameters and are consistent with a suppression in the ma gnitude of the ordered moments below T-c when compared with previously obtained neutron-scattering data.